title: Synthesis and structural study of variously oxidized diastereomeric 5'-dimethoxytrityl-thymidine-3'-O-[O-(2-cyanoethyl)-N,N-diisopropyl]-phosphoramidite derivatives. Comparison of the effects of the P=O, P=S, and P=Se functions on the NMR spectral and chromatographic properties.
abstract: R(P)- and S(P)-diastereomers of 5'-dimethoxytrityl-thymidine-3'-O-[O-(2-cyanoethyl)-N,N-diisopropyl]-phosphoramidite (T-CED) were separated by silica gel chromatography. Oxidation of both isomers with H(2)O(2), elemental sulfur and selenium, respectively, resulted in the corresponding oxidized analogues in nearly quantitative yields. All reactions were found to proceed with retention of P-configuration. This was confirmed by thorough NMR analysis which, in addition, aimed to study the spectral properties of the diastereomers with special respect to differences in the heteroatom effect of the O, S and Se atoms, double-bonded to the phosphorus, on the vicinal carbon-phosphorus couplings. It was found that the changes in the DeltaJ (=(3)J(P,C4') - (3)J(P,C2')) values were basically induced by the electronegativity of the heteroatoms, rather than differences in the rotational preferences about the C3'-O3' bond. The impact of the benzene solvent on the above couplings is also discussed. The effect of these heteroatoms on the chromatographic (normal and reverse phase HPLC) behavior of the compounds was also investigated and the reverse phase HPLC profiles showed an unambiguous correlation between the electronegativity of the heteroatoms and the chromatographic mobility of the analogues.
authors.affiliation: Institute of Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, 1025 Budapest, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Gács-Baitz
authors.forename: Ferenc
authors.initials: F
authors.lastname: Sipos
authors.forename: Orsolya
authors.initials: O
authors.lastname: Egyed
authors.forename: Gyula
authors.initials: G
authors.lastname: Sági
mesh_terms: D000241:Adenosine; D002845:Chromatography; D002851:Chromatography, High Pressure Liquid; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008190:Lyases / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen; D010758:Phosphorus / Q000737:chemistry*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D009943:Organophosphorus Compounds; D010758:Phosphorus; C049676:diisopropyl phosphoramidite; D004247:DNA; D006861:Hydrogen Peroxide; D008190:Lyases; C051328:carbon-phosphorus lyase; D000241:Adenosine; D010100:Oxygen